Some neurological disorders, such as epilepsy, are characterized by the occurrence of seizures. Seizures may be attributable to abnormal electrical activity of a group of brain cells. A seizure may occur when the electrical activity of certain regions of the brain, or even the entire brain, becomes abnormally synchronized. The onset of a seizure may be debilitating. For example, the onset of a seizure may result in involuntary changes in body movement, body function, sensation, awareness or behavior (e.g., an altered mental state). In some cases, each seizure may cause some damage to the brain, which ma result in progressive loss of brain function over time.
A therapy system may be used to manage a seizure disorder of a patient, e.g., to mitigate the effects of the seizure disorder, shorten the duration of seizures, prevent the onset of seizures, or notify a patient about an onset or potential onset of a seizure. For example, attempts to manage seizures have included the delivery of electrical stimulation to regions of the brain via a medical device and/or the delivery of drugs either orally or infused directly into regions of the brain via a medical device. In some electrical stimulation systems, a medical lead may be implanted within a patient and coupled to an external or implanted electrical stimulator. The target stimulation site within the brain or elsewhere may differ between patients, and may depend upon the type of seizures being treated by the electrical stimulation system. In automatic drug delivery systems, a catheter may be implanted within a patient and coupled to an external or implanted fluid delivery device. The fluid delivery device may deliver a dose of an anti-seizure drug into the blood stream or into a region of the brain of the patient. In either case, the therapy system may deliver therapy to manage a seizure disorder of a patient continuously, at regular intervals, and/or upon the detection of some event, such as the detection of a seizure by electroencephalogram (EEG) or electrocorticogram (ECoG) sensors implanted within the brain, or at the direction of the patient or clinician.